Well good for you for deciding to do this so young!!!
I was 19 going into boot camp... one of my shipmates was only 17 as well. The biggest difference i can see for us younger folks is that we are still young in experience and heart.
Just as a general rule... the sudden shift of life style and added stress will possibly throw you for a greater loop than some of your older shipmates. However, that should by no means stop you.
Honestly, i would take your age as something to boost your confidence... not many young people choose such a path. so like i said... good for you.
Heads up... its ok to get things wrong and feel stupid and miss mom or dad... or home... or friends ... or your dog. I didnt sleep for a week because i was so stressed and homesick. Pray that doesnt happen to you but my point is... Stuff happens but its not going to be your age that affects it. Its going to be what you choose to make of it.
As for the birthday... some company commanders do have "parties" for recruits birthdays... parties meaning IT sessions. The shipmates i knew (about 07 of em) that had birthdays in boot camp... were treated just as before. And if you do get unwanted attention... remember its on a schedule... and they were just making an excuse to IT you but if they didnt have one... they would do it anyways...
Just give it your best and never doubt yourself because of your age.
You are going to do great!
thank you for choosing to serve.